Every day, up to 3 billion microplastic particles flow down the Ganges into the ocean A group of scientists studying the flow of plastic in the ocean has just discovered the staggering amounts of microplastic particles that the largest river in south Asia supplies the ocean each day.

Scientists have calculated that the Ganges and two surrounding waterways are responsible for dumping 3 billion microplastics into the Indian Ocean each day. The research was carried out as part of a National Geographic project called Sea to Source, which aims to trace how ocean pollution can be reduced. In December, the team working on this project published such details of their work, such as how far the marked plastic bottles can go on the Ganges, and today we learned more details.

Using their previous experiments, the researchers conducted what they call the first investigation of microplastic abundance in the Ganges River, collecting samples from 10 sites both in the pre- and post-monsoon season. In a laboratory at the University of Plymouth, UK, they analyzed the collected samples to find that 72% of the pre-monsoons contained microplastic with particles measuring less than 5 mm, and in the case of the post-monsoons, 62% of the samples. Over 90% of all microplastics were fibers common in clothing such as acrylic and rayon.

The Ganges is an enormous 2,700 km river that has its origins in the Himalayas, flows through India and Bangladesh, and then flows into the Bay of Bengal, part of the Indian Ocean. It also connects to the Brahmaputra and Meghna rivers on the way, so scientists took all three rivers into account and found that they collectively deliver between 1 billion and 3 billion microplastic particles into the ocean each day. And since this basin is one of the most densely populated in the world, it is a source of water - full of plastic - for 655 million people.

From the research, we also learn about various places in the river that are exposed to particular pollution, and areas representing rural, urban, agricultural, tourist and religious areas were taken into account. The greatest amounts were found at tech boy world mouth of the river in Bangladesh, where the concentration was four times higher than at the source. - We know that sources are a key source of microplastics in the ocean. But information like this helps us identify the key sources and pathways of microplastics and intervene on that basis. With this kind of evidence, we can make progress in smarter plastic use and avoid a lot of unnecessary environmental contamination, 'explains Professor Richard Thompson, co-author of the study.

/University of Plymouth